Grignard Exchange Reaction

Another pilot plant, developed by at Kyoto University, was used for the Grignard exchange reaction at the same productivity as the batch reactor (10 m3) by adding only four microflow systems of the present scale (Wakami and Yoshida 2006). A multitubular reactor is the core element of the microprocessing plant (see Fig. 17). Stable yields of approximately 95% could be demonstrated for a 24-h run. 

Fig. 17. Multitubular reactor used for the Grignard exchange reaction pilot microprocess plant. (Courtesy of ACS)...

Grignard exchange reactions of sulfoxides substituted with groups other than azaheterocycles proceed mostly by an inversion on the sulfur atom there are a few exceptions (73S485 74CJC761). As shown in reactions (15) and (16), optically active dialkyl sulfoxides can be prepared starting from... 

Figure 5.19 Microprocess pilot plant for Grignard exchange reaction (by courtesy of ACS) [56],...

Scheme 4 Proposed reaction course for titanium-catalyzed Grignard exchange reaction...

Scheme 7 Proposed reaction course for nickel-catalyzed Grignard exchange reactions...

Like other hydromagnesations catalyzed by iron [3,53,54] or cobalt [55], further synthetic applications of these nickel-catalyzed Grignard exchange reactions were not examined in more detail. 

Of the aforementioned transition metal-catalyzed Grignard exchange reactions, the most standard method that has the broadest applications in organic synthesis is perhaps a titanium-catalyzed hydromagnesation of olefins and acetylenes with low molecular weight Grignard reagents. 

Figure 8.6 Grignard exchange reaction of C2F5I with MeMgCl followed by reaction with benzophenone in a microflow system...

Other transition metal-mediated hydromagnesi-ations involve a nickel-catalyzed reaction [9,I(X). However, except for the reaction of eq. (3.56) ]9], further synthetic application of this nickel-catalyzed Grignard exchange reaction has not been examined in more detail. 

Titanium calaly/ed Grignard exchange reaction 74 Titanium-enlaly/cd hydromagnesiaiion of ololins and acetylenes 93... 

SCHEME 3.5. Proposed reaction course for the titanium-cataly/ed Grignard exchange reaction. 

Benzyne can be produced by the reaction of o-chloro- or o-bromosulfoxides (15) with Grignard reagents. When X = Br or Cl, Grignard exchange occurs mainly at the sulfoxide... 

Grignard exchange reaction Pentafluorobenzene 92% Formation of Grignard reagents 2005/[43]... 

Wakami, H. and J. Yoshida, Grignard exchange reaction using a microflow system From bench to pilot plant. Organic Process Research and Development, 2005, 9 787-791. 

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